The present invention relates to medical devices, and, more particularly, to implantable medical devices.
Typically, patients with heart failure have a reduced capacity for myocardial function. The heart is unable to adequately meet the metabolic demands of the body by providing the appropriate blood flow. This may result in increased blood pressure (afterload), and increased volume retention (preload). Thus, common symptoms of heart failure or ventricular dysfunction include fatigue, which is caused by the low cardiac output, and edema and swelling, which is caused by fluid overload.
In patients with heart failure, on-going ambulatory monitoring of the heart conditions can be an important factor in successful cardiac disease management. Such ambulatory monitoring of the patient can often involve the collection of parameters such as heart rate, pressure, temperature, etc. As is known, the monitoring of one or more of these parameters can be achieved through the use of one or more implantable medical devices (IMDs), such as pacemakers, defibrillators, monitors, etc. Following transfer of these parameters from the IMD(s) to a clinical center, a medical professional, after subsequent analysis, can generally provide final diagnoses concerning the patient.
However, quite often, the collection of these parameters can be limited by the location of the IMD electrode and/or the fixed storage memory size of the IMD. In turn, it can be difficult for the medical professional to identify arrhythmias based on these parameters because of the above limiting factors or other factors. As such, it can also be difficult for the medical professional to routinely provide accurate diagnoses for the patient because of uncertainty regarding whether the parameters are representative of a worsening state of the patient's heart, or conversely, due to an arrhythmic event.
Certain embodiments of the invention are directed to overcoming, or at least reducing the effects of, one or more of the limitations set forth above.